xref: /freebsd/sys/contrib/openzfs/lib/libspl/os/linux/zone.c (revision b197d4b893974c9eb4d7b38704c6d5c486235d6f)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or https://opensource.org/licenses/CDDL-1.0.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 /*
22  * Copyright 2006 Ricardo Correia.  All rights reserved.
23  * Use is subject to license terms.
24  */
25 
26 #include <unistd.h>
27 #include <stdio.h>
28 #include <errno.h>
29 #include <stdlib.h>
30 #include <limits.h>
31 #include <string.h>
32 
33 #include <zone.h>
34 
35 zoneid_t
36 getzoneid(void)
37 {
38 	char path[PATH_MAX];
39 	char buf[128] = { '\0' };
40 	char *cp;
41 
42 	int c = snprintf(path, sizeof (path), "/proc/self/ns/user");
43 	/* This API doesn't have any error checking... */
44 	if (c < 0)
45 		return (0);
46 
47 	ssize_t r = readlink(path, buf, sizeof (buf) - 1);
48 	if (r < 0)
49 		return (0);
50 
51 	cp = strchr(buf, '[');
52 	if (cp == NULL)
53 		return (0);
54 	cp++;
55 
56 	unsigned long n = strtoul(cp, NULL, 10);
57 	if (n == ULONG_MAX && errno == ERANGE)
58 		return (0);
59 	zoneid_t z = (zoneid_t)n;
60 
61 	return (z);
62 }
63